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Commit abe59c65 authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Antonio Quartulli
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batman-adv: Fix reference counting of hardif_neigh_node object for neigh_node 



The batadv_neigh_node was specific to a batadv_hardif_neigh_node and held
an implicit reference to it. But this reference was never stored in form of
a pointer in the batadv_neigh_node itself. Instead
batadv_neigh_node_release depends on a consistent state of
hard_iface->neigh_list and that batadv_hardif_neigh_get always returns the
batadv_hardif_neigh_node object which it has a reference for. But
batadv_hardif_neigh_get cannot guarantee that because it is working only
with rcu_read_lock on this list. It can therefore happen that a neigh_addr
is in this list twice or that batadv_hardif_neigh_get cannot find the
batadv_hardif_neigh_node for an neigh_addr due to some other list
operations taking place at the same time.

Instead add a batadv_hardif_neigh_node pointer directly in
batadv_neigh_node which will be used for the reference counter decremented
on release of batadv_neigh_node.

Fixes: cef63419 ("batman-adv: add list of unique single hop neighbors per hard-interface")
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: default avatarAntonio Quartulli <a@unstable.cc>
parent a33d970d

net/batman-adv/originator.c

+5 −11
Original line number Diff line number Diff line
@@ -250,7 +250,6 @@ static void batadv_neigh_node_release(struct kref *ref) 
{

	struct hlist_node *node_tmp;

	struct batadv_neigh_node *neigh_node;

	struct batadv_hardif_neigh_node *hardif_neigh;

	struct batadv_neigh_ifinfo *neigh_ifinfo;

	struct batadv_algo_ops *bao;
@@ -262,13 +261,7 @@ static void batadv_neigh_node_release(struct kref *ref) 
		batadv_neigh_ifinfo_put(neigh_ifinfo);

	}



	hardif_neigh = batadv_hardif_neigh_get(neigh_node->if_incoming,

					       neigh_node->addr);

	if (hardif_neigh) {

		/* batadv_hardif_neigh_get() increases refcount too */

		batadv_hardif_neigh_put(hardif_neigh);

		batadv_hardif_neigh_put(hardif_neigh);

	}

	batadv_hardif_neigh_put(neigh_node->hardif_neigh);



	if (bao->bat_neigh_free)

		bao->bat_neigh_free(neigh_node);
@@ -665,6 +658,10 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, 
	neigh_node->orig_node = orig_node;

	neigh_node->last_seen = jiffies;



	/* increment unique neighbor refcount */

	kref_get(&hardif_neigh->refcount);

	neigh_node->hardif_neigh = hardif_neigh;



	/* extra reference for return */

	kref_init(&neigh_node->refcount);

	kref_get(&neigh_node->refcount);
@@ -673,9 +670,6 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, 
	hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);

	spin_unlock_bh(&orig_node->neigh_list_lock);



	/* increment unique neighbor refcount */

	kref_get(&hardif_neigh->refcount);



	batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv,

		   "Creating new neighbor %pM for orig_node %pM on interface %s\n",

		   neigh_addr, orig_node->orig, hard_iface->net_dev->name);

net/batman-adv/types.h

+2 −0
Original line number Diff line number Diff line
@@ -433,6 +433,7 @@ struct batadv_hardif_neigh_node { 
 * @ifinfo_lock: lock protecting private ifinfo members and list

 * @if_incoming: pointer to incoming hard-interface

 * @last_seen: when last packet via this neighbor was received

 * @hardif_neigh: hardif_neigh of this neighbor

 * @refcount: number of contexts the object is used

 * @rcu: struct used for freeing in an RCU-safe manner

 */
@@ -444,6 +445,7 @@ struct batadv_neigh_node { 
	spinlock_t ifinfo_lock;	/* protects ifinfo_list and its members */

	struct batadv_hard_iface *if_incoming;

	unsigned long last_seen;

	struct batadv_hardif_neigh_node *hardif_neigh;

	struct kref refcount;

	struct rcu_head rcu;

};